The invention relates to all kinds of lifting curtain doors including a winding shaft which is rotated by a motor external to said shaft. Doors of this type are used essentially for two distinct and incompatible purposes: some are intended to provide protection against intrusion, in which case the curtains are rigid and are generally constituted of hinged metal gratings or sheets which are relatively heavy and which operate relatively slowly; others are intended to facilitate goods handling while constituting a thermal screen, in which case they comprise flexible curtains which are generally made of plastified cloth (or of plastic film) which may optionally be stiffened at regular intervals by horizontal reinforcing bars, but which are light and which operate rapidly. Apart from their different purposes and their different constructions, all such doors to which the invention is equally applicable include a winding shaft on which either the curtain itself is wound (as is the case for protective doors and some handling doors) or else curtain-lifting straps are wound (as is the case for concertina-type handling doors, for example).
In order to explain in detail how the winding shaft of a lifting curtain door is normally supported and driven, regardless of whether the door is for handling purposes or for protection purposes, FIG. 1 is a diagrammatic perspective view of the top of a handling door whose shaft is used for winding up lifting straps. This door may be a concertine-type door, for example, having its curtain 1 constituted by a rectangle of plastified cloth which is stiffened at regular intervals by horizontal reinforcing bars (not shown). The curtain is lifted by the straps 2 each having one end connected to the bottom reinforcing bar and having its other end fixed on a winding shaft 3. The straps also pass through guides in the form of rectangular loops which are fixed on all odd-numbered reinforcing bars counting from the bottom bar. As a result, when the straps 2 are wound onto the shaft 3, the flexible curtain 1 is raised while being folded concertina-like. The door shown in FIG. 1 comprises two channel section vertical risers 4 receiving the ends of the reinforcing bars, and a horizontal crossbeam 5 interconnecting the risers 4 and supporting the door drive assembly, and having the top edge of the curtain 1 fixed thereto. The drive assembly comprises the winding shaft 3 which is mounted to rotate freely in at least two supports 6 fitted with ball-bearings 6', together with an electric motor 7 which is coupled via a stepdown gear 8 whose axis is parallel to the axis of the shaft 3, said motor driving said shaft via a transmission chain 9 and a pair of sprocket wheels 9' and 9". The drive assembly also includes an emergency manual actuator device 10 comprising a rod and an angle coupling enabling the shaft 3 to be rotated via the stepdown gear 8. There is also an end-of-stroke assembly 11 for stopping the motor 7 when the door is fully open and when it is fully closed. This end-of-stroke assembly may be of various different types, known per se. For example, it may comprise a rod or shaft supporting a cam which is rotated simultaneously with the shaft 3. The cam acts on an electric contact of a counter which increments or decrements by one unit for each turn of the camshaft (depending on its direction of rotation) and which stops the motor 7 when a reference value corresponding to a limiting position of the curtain is reached. The end-of-stroke assembly shown in FIG. 1 comprises a threaded rod 12 constituting an endless screw parallel to the shaft 3 which is rotated by said shaft via a transmission chain 13 and two sprocket wheels 13' and 13". This threaded rod moves a cursor 14 to left or to right depending on the direction of rotation of the winding shaft 3, and the cursor controls top and bottom end-of-stroke switches 15 and 16 which interrupt the power supply to the motor 7 whenever the cursor 14 presses against one or the other of them.
Although the door described above is a particular embodiment and the disposition of its various parts could be varied (the motor could be fixed along one of the risers, so that its axis is perpendicular to the axis of the winding shaft, for example), it nevertheless remains true that all lifting curtain doors include similar supports and drive means for their winding shafts. However, as can be seen from the above description, such apparatus includes numerous parts: there are support parts per se, such as the crossbeam 5, the supports 6, and the ball-bearings 6'; there are transmission and stepdown parts such as the stepdown gear 8, the transmission chains 9 and 13, and the sprocket wheels 9' and 9" and 13' and 14"; and there are driving or control parts such as the motor 7 and the end-of-stroke means 11. In practice, this set of parts constitutes an operating minimum and various other support parts (in particular the crossbeam 5) and fixing parts necessary for assembling said operating parts are required in order to be able to fit doors to spaces of given dimensions. Naturally, consideration time and manpower are required to make such additional parts and to mount the above-mentioned set of parts carefully, since they need to be positioned relative to one another quite accurately. In addition, the provision of numerous transmission members and of multiple fixing points increases the risk of subsequent breakdown.
The aim of the present invention is to remedy these drawbacks. The present invention seeks to provide a support and transmission module for the winding shaft of a lifting curtain door which, in combination with another module of the same type, replaces the crossbeam 5, the supports 6 together with their bearings 6', the sprocket wheels 9' and 9" and 13' and 13" together with their transmission chains 9 and 13, and the stepdown gear 8 of doors as presently manufactured, thereby providing means which can be easily and quickly installed, which are capable of industrial prefabrication, and which are completely reliable. In addition, the invention provides numerous variants of such a module suitable for shafts of any length, and in particular very long shafts comprising a plurality of lengths, and also shafts which deform as they rotate (which happens to shafts used for winding up lifting straps, in particular).